Folding a bun so it does not open in the oven

This is the single thing people come back and ask us about after a class. The bun looked perfect going in and came out of the oven with its filling on the tray. It is fixable, and it is nearly always one of four things.

Cook the filling down further than feels right

Heat turns liquid into steam and steam has to go somewhere. If your filling loosens on a spoon, it will flood the seam. A filling ready for a bun should hold a shape when you push it with the back of a spoon and should not weep after five minutes on a plate.

Chill it. A cold filling is firmer, sits still while you work, and does not start melting the butter in the dough. We make fillings the day before for exactly this reason.

Weigh, do not eye it

Forty grams of dough takes twenty five grams of filling comfortably. Thirty five grams and you are gambling. A kitchen scale does more for a bun than any amount of technique.

Leave a clean rim

Flatten the dough so it is thicker in the middle and thinner at the edge, then keep a clear centimetre and a half of dry dough all the way round. Any filling that touches that rim stops it sticking, and one greasy patch is enough to open the whole seam.

Pleat, pinch, then turn it over

Gather the edge in small folds, working around in one direction, and pinch the last pleat into the first. Then twist the gathered point gently and press it flat. Sit the bun seam side down on the tray so its own weight is holding the join shut while it proves.

Egg wash the top only. Wash that runs down into a seam glues it about as well as water does.

If it still splits

A split on the side means the seam was stretched thin. A split on the top with filling showing means overfilled. A blowout with liquid means the filling was too wet. A crack with nothing coming out is just oven spring, and is fine.

We work through all of this by hand in A Filled Bun Afternoon, and the same fold closes the steamed buns too, only pleated more tightly because there is no crust to help.